Guido Sessa, and
Christine D. Smart
First and third authors: Department of Plant Pathology and Plant-Microbe Biology, Cornell University, New York State Agricultural Experiment Station, Geneva 14456; and second author: Department of Plant Sciences, Tel-Aviv University, 69978 Tel-Aviv, Israel.
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Accepted for publication 27 October 2010.
Clavibacter michiganensis subsp. michiganensis is an actinomycete, causing bacterial wilt and canker disease of tomato (Solanum lycopersicum). We used virus-induced gene silencing (VIGS) to identify genes playing a role in host basal defense response to C. michiganensis subsp. michiganensis infection using Nicotiana benthamiana as a model plant. A preliminary VIGS screen comprising 160 genes from tomato known to be involved in defense-related signaling identified a set of 14 genes whose suppression led to altered host–pathogen interactions. Expression of each of these genes and three additional targets was then suppressed in larger-scale VIGS experiments and the effect of silencing on development of wilt disease symptoms and bacterial growth during an N. benthamiana–C. michiganensis subsp. michiganensis compatible interaction was determined. Disease susceptibility and in planta bacterial population size were enhanced by silencing genes encoding N. benthamiana homologs of ubiquitin activating enzyme, snakin-2, extensin-like protein, divinyl ether synthase, 3-hydroxy-3-methylglutaryl-coenzyme A reductase 2, and Pto-like kinase. The identification of genes having a role in the host basal defense-response to C. michiganensis subsp. michiganensis advances our understanding of the plant responses activated by C. michiganensis subsp. michiganensis and raises possibilities for devising novel and effective molecular strategies to control bacterial canker and wilt in tomato.
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